Substitution coefficient $\Delta_2$ for eddy-currents

Symbol
$\Delta_{2}$
Formulas
$0$trefoil arrangement and non-flat formations
$21{m_{0}}^{3.3} \left(\frac{d_{e}}{2s_{c}}\right)^{1.47m_{0}+5.06}$flat formation, other outer phase (leading 3/T/W)
$0$flat formation, middle phase (1/R/U)
$0.92{m_{0}}^{3.7} \left(\frac{d_{e}}{2s_{c}}\right)^{m_{0}+2}$flat formation, outer phase with greater loss (lagging 2/S/V)